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Membrane fouling and high-strength membrane concentrate production are two limitations of membrane distillation (MD) for landfill leachate treatment. In this study, activated carbon- and biochar-based adsorption processes were integrated into a conventional MD system to overcome these limitations. The organic matter fractionations of the leachate were thoroughly investigated during the treatment. Membrane-reversible and irreversible foulants differed remarkably from the inlet leachate in the non-assisted MD system. Specifically, reversible foulants were characterized by a high abundance of humic-like fluorescent components, high-molecular-weight humic-size constituents, peptides, and unsaturated compounds. In contrast, irreversible foulants were enriched with fulvic-like fluorescent components, low-molecular-weight neutrals, unsaturated compounds, and polyphenols. The adsorption-based pre-treatment effectively removed foulant precursors from landfill leachate, with a relatively higher (20%) adsorption performance for specific biochar used in this study than for activated carbon. Compared with the non-assisted MD system, the biochar-assisted MD system showed improved performance, achieving 40% overall membrane flux recovery, 42% higher filtration fluxes, and 53% lower concentrate production. In addition, a 15% higher removal of irreversible foulants was observed as compared to the reversible foulants, which can potentially increase the membrane lifespan. This study demonstrates the effectiveness of an adsorption-assisted MD system supported by increased filtration, membrane fouling alleviation, and low-strength leachate concentrate generation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

A composite manganese-based catalytic ceramic membrane (Mn-CCM) was developed by a solid-state sintering method, and its effectiveness toward activation of peroxymonosulfate (PMS) for the degradation of 11 pharmaceutical and personal care products (PPCPs) mixture was tested. The optimized Mn-CCMs/PMS system showed remarkable degradation efficiencies for PPCPs mixture with total removal >90% in ultrapure water, river water and natural organic matter (NOM) solution. The Mn-CCMs/PMS system showed the contribution of different phenomena in PPCPs removal in the order of catalytic oxidation (54.7%, Mn-CCMs/PMS) > noncatalytic oxidation (42.3%, PMS oxidation) > adsorption (3.0%, by Mn-CCMs). The singlet oxygen ( 1 O 2 ) was the dominant reactive oxygen specie for the degradation of PPCPs in all water matrices proved by the quenching experiments and electro-paramagnetic resonance (EPR) spectroscopy. The extraordinary stability of Mn-CCMs for the activation of PMS has been noted in terms of repeatability experiments for PPCPs degradation with fewer leaching of Mn (1.9 to 3.6 µg/L). Mineralization was achieved in the range of 28-65% for different water matrices. The toxicity of the PPCPs mixture was reduced by 85.9%. The Mn-CCMs/PMS system showed a reduction (25-100%) in precursors of different carbon- and nitrogen-based disinfection by-products. This study found the Mn-CCMs/PMS system as a feasible purification unit for removing trace concentrations of PPCPs (ng/L) in real drinking water matrices., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Applications of electrochemical advanced oxidation processes are rising in drinking water treatment for effective mitigation of refractory organic compounds. This study explored the fate of natural organic matter (NOM) (lake water and standard NOM (SRNOM solution)) at molecular-level in the reactive electrochemical membrane (REM) system utilizing Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Fluorescence spectroscopy showed above 90 % removal of the humic-like component in both lake water and SRNOM solution in 10 min of REM operation compared to 70-80 % removal of the fulvic-like component after 30 min. REM-based treatment effectively eliminated (>70 %) the disinfection byproduct precursors. The lake water, sharing ~70 % of similar compounds with SRNOM, displayed a different propensity toward electrochemical oxidation, and its finished water was characterized with relatively lower double-bond equivalent (DBE), nominal oxidation state of carbon (NOSC), and aromaticity compared to that of SRNOM. The chloride ions in the water matrix of lake water impacted the electrochemical oxidation and generated significantly different transformation products than SRNOM solution. The heteroatoms (N and S) containing compounds (CHON and CHOS) were preferentially degraded in lake water; however, CHOS compounds were removed fewer in SRNOM. The electrosorption and electrochemical oxidation on the REM surface were the significant contributors for NOM removal. The newly formed compounds were mostly retained on the REM surface and fewer were released in finished water. This study is believed to help understand the fate of NOM in real source drinking water during electrochemical treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Herein, a biosorbent was prepared from cucumber peels modified with ZnO nanoparticles (CPZiONp-composite) for the biosorption of metribuzin. Characterization of the composite was accomplished using FTIR, SEM, EDX, surface area pore size analyzer and pH of point of zero charge (pH pzc ). Biosorption study was executed in batch concerning the impact of pH, composite dose, contact time, initial metribuzin concentration and temperature. The biosorption depends on pH and maximum biosorption was acquired at pH 3.0. Surface chemistry of the composite was studied by determining the pH pzc and was found to be 6.1. The biosorption nature was investigated using isotherms and was assessed that Freundlich isotherm is well suited for the fitting of the biosorption data owing to the highest R 2 . The maximum biosorption capacity of CPZiONp-composite was found to be 200 mg g -1 . The biosorption data were fitted in to different kinetic models and the outcomes suggesting that pseudo second order is a satisfactory model to interpret the biosorption data owing to the highest R 2 . Thermodynamic parameters for instance entropy, enthalpy and Gibbs free energy were computed and revealed that biosorption of metribuzin onto CPZiONp-composite is spontaneous and exothermic process., (© 2022. The Author(s).)

The occurrence of mutagenic and carcinogenic N-nitrosamines in drinking water is of great concern. In this study, dynamics and removal of nine N-nitrosamines in three drinking water treatment systems of a southern city of China are monitored during one year of sampling. The impacts of physicochemical treatment units on the removal and generation of N-nitrosamines were evaluated. The O 3 and KMnO 4 based pre-oxidation units have caused an increase in N-nitrosamines concentration, with O 3 showing the substantial generation of N-nitrosamines. The carbon filter and ultrafiltration membrane units were found effective in removing N-nitrosamine precursors. These drinking water treatment systems have been useful in removing N-nitrosamine precursors; meanwhile, a slight decrease was found in already formed N-nitrosamines concentration. However, N-nitrosomorpholine (NMOR) and N-nitrosodiphenylamine (NDPhA) were found resistant toward all kinds of physicochemical treatments, and negligible changes in concentration were noted in all drinking water treatment systems. The distribution networks in the city provided an effective contact period to residual chlorine and precursors, which caused an increase in N-nitrosamines concentration. Overall, N-nitrosodimethylamine (NDMA) and N-nitroso-diethylamine (NDEA) have been found near the cancer risk threshold (10 -6 ) in all of the drinking water treatment systems, while the remaining seven N-nitrosamines were found below the risk level., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Nanomaterials (NMs) have received tremendous attention as emerging adsorbents for environmental applications. The ever-increasing release into aquatic systems and the potential use in water treatment processes heighten the likelihood of the interactions of NMs with aquatic dissolved organic matter (DOM). Once DOM is adsorbed on NMs, it substantially modifies the surface properties, thus altering the fate and transport of NMs, as well as their toxic effects on (micro)organisms in natural and engineered systems. The environmental consequences of DOM-NMs interaction have been widely studied in the literature. In contrast, a comprehensive understanding of DOM-NM complexes, particularly regarding the controlling factors, is still lacking, and its significance has been largely overlooked. This gap in the knowledge mainly arises from the complex and heterogeneous structures of the DOM, which prompts the urgent need to further characterize the DOM properties to deepen the understanding associated with the adsorption processes on NMs. This review aims to provide in-depth insights into the complex DOM adsorption behavior onto NMs, whether they are metal- or carbon-based materials. First, we summarize the up-to-date analytical methods to characterize the DOM to unravel the underlying adsorption mechanisms. Second, the key DOM characteristics governing the adsorption processes are discussed. Next, the environmental factors, such as the nature of adsorbents and solution chemistry, affecting the DOM-NM interactions, are identified and discussed. Finally, future studies are recommended to fully understand the chemical traits of DOM upon its adsorption onto NMs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

N-nitrosamines have been identified as emerging contaminants with tremendous carcinogenic potential for human beings. This study examined the seasonal changes in the occurrence of N-nitrosamines and N-nitrosodimethylamine formation potential (NDMA-FP) in drinking water resources and potable water from 10 drinking water treatment plants in a southern city of China. The changes in N-nitrosamines are well correlated with dissolved organic matter (DOM), particularly fluorophores, which were measured and compared between traditional fluorescence indices and excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC). Four of N-nitrosamine species including N-nitrosodimethylamine (NDMA), N-Nitrosodibutylamine (NDBA), N-Nitrosopyrrolidine (NPYR), and N-Nitrosodiphenylamine (NDPhA) are found to be abundant compounds with an average of 29.5% (26.7%), 20.0% (25.2%), 18.9% (16.0%), and 9.0% (9.9%) in the source (and treated) water, respectively. The sum of N-nitrosamines concentration is recorded to be low in the wet season (July-September), whereas the dry season (October-December) provided opposite impacts. EEM-PARAFAC modeling indicated the predominance of humic-like component (C1) in the wet season while in the dry season the water was dominant in protein-like component (C2). All the N-nitrosamines excluding NDPhA and N-Nitrosomorpholine (NMOR) showed a strong association with protein-like component (C2). In contrast, humic-like C1, which was directly influenced by rainfall, was found to be a suitable proxy for NMOR and NDPhA. The results of this study are valuable to understand the correlation between different N-nitrosamines and DOM through adopting fluorescence signatures., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Ultrafiltration (UF) membrane fouling caused by terrestrial input of dissolved organic matter (DOM), especially during high flood periods, is poorly understood. In this study, we examined the fouling characteristics of three different terrestrial humic substances (HS) on regenerated cellulose (RC) UF membranes with the pore sizes of 30 k-3 kDa via conventional bulk HS measurements as well as an advanced fluorescence spectroscopy. The fluorescence excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC) identified one protein-like (C1) and three humic-like fluorescent components (C2-C4) from soil and leaf-derived HS. The fate of the different fluorescent components was individually tracked for the UF processes. The higher removal rates were found generally on the order of high molecular weight (HMW) C1 to smaller sized humic-like components (C4 > C3 > C2) regardless of the HS sources, implying the importance of HS molecular sizes on the UF operation. Among the humic-like components, C2 was the most associated with irreversible fouling, while other two humic-like components contributed more to reversible fouling. For soil-derived HS, C4 can be suggested as a good surrogate for membrane fouling, as evidenced by the highest correlation between the removal rates and the total fouling indices among the tested HS variables including conventional bulk parameters. Our study demonstrated a promising application of EEM-PARAFAC for probing membrane fouling of terrestrial DOM, which provided additional insight into the fate of different fluorescent components on the UF processes., (Copyright © 2016 Elsevier Ltd. All rights reserved.)